I was in your mom's shoes 12 years ago except my complex cyst was smaller. My gyn also urged me to see a gyn oncologist but said I probably wouldn't have time because surgery needed to be done quickly. I allowed these fear tactics to overtake my thoughts and actions. I wish I had done things very differently and realized that ~90% of female organ removals are unnecessary.
The frozen section done while I was in the operating room was benign but my gyn removed all my female organs anyway. The loss of those vital hormones destroyed everything about me. The ovaries produce hormones a woman's whole life to keep her physically, mentally and emotionally healthy. The uterus also has lifelong functions.
Most ovarian cysts, even large complex ones, are benign. Ovarian cancer is rare; 1.3% lifetime risk for the average woman.
Medical literature clearly shows that removal of one or multiple female organs (uterus, ovary / ovaries) causes permanent harm.
Surgeons with good cystectomy skills can remove most cysts and save the ovary. Check out the cyst section on ovaryresearch.com.
I hope this helps!